The present invention relates to a probe card for testing a semiconductor device and a semiconductor substrate.
When manufacturing a semiconductor device, a probing test is normally conducted to test the conductivity of a wafer. In the probing test, a plurality of probes respectively contact a plurality of pads, which are formed on the wafer. Various properties of the semiconductor device are measured in accordance with probing test programs. The enlargement of recent semiconductor circuits has increased the number of pads. However, the area of each pad has decreased. To shorten the time required for the probing test, it is important that the contact between the probes and the pads be guaranteed.
A probe card, which has a plurality of probes, is used during the probing test. A probing device causes the probes to contact the pads of a wafer with a predetermined contact pressure. More specifically, referring to FIG. 1A, the probing device causes each probe pin 3 to approach a corresponding pad 2, which is formed on a wafer substrate 1. Then, the probing device lifts the wafer substrate 1 by distance A and presses the pad 2 against the probe pin 3.
In the prior art, the distance A must be great enough to guarantee that each probe pin 3 contacts the pad 2. However, as the wafer substrate 1 rises, the distal end of the probe pin 3 bites into the pad 2 and moves in the direction indicated by arrow B. This removes the surface of the pad 2 and forms a pit 4 (FIG. 2). If the distance A is too large, the pit 4 becomes relatively long (large), and a relatively large amount of material, which is removed from the pad 2, is adhered to the distal end of the probe pin 3.
The recent pads are thin. Thus, the distal ends of the probe pins 3 may reach the underlying layers of the pads 2. In such case, metal material, such as aluminum (Al), gold (Au), and nickel (Ni), may adhere to the distal ends of the probe pins 3. When the probing device tests a plurality of electronic devices, the probe pins 3 are repetitively pressed against the corresponding pads 2 of the electronic devices. This deposits the materials of the pads 2 and the underlying layers on the distal ends of the probe pins 3. The deposition of the materials causes contact failure between the probe pins 3 and the pads 2 and decreases the reliability of the probing test.
Due to the higher integration and increased functions of recent electronic devices, many complicated tests must be conducted during the probing test. Thus, the probe pins 3 repetitively contact the same pads 2. In such case, the probe pins 3 repetitively remove material from the corresponding pads 2 and enlarge the pits 4. This results in bonding deficiencies between bonding wires and the pads 2 during a subsequent bonding process.
An increase in the number of pads has increased the number of probes. Thus, a probe card nowadays has 600 to 800 and in some cases more than 1,000 probes that are arranged with a narrow interval between one another. To arrange a large number of probes on a probe card, the inclination angle α between the pads 2 and the corresponding probe pins 3 is relatively small. As a result, it is difficult for the probe pins 3 to contact the pads with sufficient pressure.
Japanese Laid-Open Patent Publication No. 11-142437 describes a probe card provided with a guide plate having a guide hole to guide a probe pin. Although the probe card increases the positioning accuracy of the probe pin, it is difficult to optimally adjust the contact pressure between the probe pin and the pad. Further, the guide hole must be machined with high accuracy. This increases the manufacturing cost of the probing device.
Japanese Laid-Open Patent Publication No. 2000-327402 describes the material of a guide that guides a probe. The material enables fine machining of the guide and improves the accuracy of the contact position between the probe and the pad. However, since the guide is made of a special material, the cost of the probing device increases.
Japanese Laid-Open Patent Publication No. 2001-108708 describes a probe card having a guide that decreases the moving amount of the probe relative to the pad. However, the guide requires high machining accuracy. This increases the manufacturing cost of the probe card. Further, it is difficult to have the probe, which becomes thinner at positions closer to the distal end, contact the pad with sufficient contact pressure.